It has been proposed to provide a detachable coupling system to such a submergible pump of the type above so as to effect coupling and decoupling without need of access by an operator to the place where the conduit and the pump is coupled. Such coupling system is desired because the submergible pump may be immersed in filthy water or sewage for discharging the same through the conduit. (Decoupling operation of such pump is required, for example, to perform inspection and maintenance of the pump.) Further, in case of filthy water or sewage, even should the operator have access to the pump, the opacity or turbidity of the filthy water would prevent him from observing the coupling portion. Thus, such submergible pump having such a detachable coupling system as above has been simply lowered into or lifted from the water by an operator standing at the place above the surface of the water. Most of the detachable coupling system of the above type rely substantially on the weight of the pump for mating a discharge port of the pump to an inlet end of the discharge conduit with the pump being hung by a rope or chain so that the weight of the pump urges the pump toward the inlet end of the conduit.
For accomplishing the above matter, there have been proposed several approaches, for example, as disclosed in U.S. Pat. Nos. 3,861,834; 3,880,553; 4,060,345; 3,427,982; 3,018,925; Japanese Utility Model Public Disclosure No. 134101/78 and Japanese Patent Public Disclosure No. 107602/77.
In the prior art noted above, a submergible pump is hung by a rope or chain to be lifted from and lowered into the water and means is generally provided to keep the pump properly orientated for assuring the proper coupling of the pump with the discharge conduit. Such means is usually a pair of guide rails or bars such as disclosed in U.S. Pat. Nos. 3,880,553; 3,427,982 and Japanese Patent Public Disclosure No. 107602/77. Such provision of two guide rails or bars is made to prevent the rotation of the pump during its descending as occurs if the guide is a single round rod. However, the provision of such two guide rails increases the size of the plan view of the pump in combination with the guide rails (as viewed in a direction parallel to the guide rails) whereby it may become necessary to increase the size or diameter of a manhole in case the submergible pump is used in the manhole. Further, an element to be attached to the pump housing for guiding the pump along the guide rails also becomes large. Such increase in size makes the pump inconvenient to handle and, also, increases the manufacturing cost. In contrast to the above, there is another approach such as disclosed in U.S. Pat. Nos. 3,861,834 and 4,060,345 wherein an aligning rail is attached to the pipe guide (which serves as a discharge conduit also) to assist the proper orientation of the pump just before coupling is effected. Since the aligning rail is attached at the lower part of the guide, there still remains a problem in that the pump rotates around the guide and some adjustment is required to align the pump side element with the aligning rail. This is troublesome and also may require stopping the descent of the pump temporarily and cause damage to the system.
Also, in the prior art, engaging means have been commonly employed to fasten or hold the pump to the stationary discharge conduit during the period that the two are mated and coupled so that the discharge port of the pump is maintained in place with sealing engagement with the inlet end of the discharge conduit. Usually the discharge port of the pump is provided with a flange and, similarly the inlet end of the conduit is provided with a flange so that the two flanges sealingly mate with each other when the pump is lowered into the water along the guide. The respective coupling means of the conduit and the pump are arranged so that they first contact each other during the descending of the pump and the coupling means attached to the pump further moves downwardly as the pump continues to descend until it finally rests at a position which is determined together with the opposite coupling means mounted on the stationary discharge conduit. When the coupling means attached to the pump reaches its final position, the flanges of both the pump and the discharge conduit are adapted to sealingly mate with each other due to a component force of the gravity which urges the pump flange against the flange of the discharge conduit. The conventional coupling means are a combination of a cam and a follower or followers, wedge shaped members or the like designed to prevent relative separation of the pump and conduit at the final (lowered) operative position of the pump. Therefore, the locations and accuracy of the coupling means relative to the flanges of the pump and the conduit are important, and the fabrication of those means has been relatively time consuming and expensive.
In Japanese Utility Model Public Disclosure No. 134101/78, a single guide bar is employed to solve some of the drawbacks of the prior art; however, this is not completely satisfactory since the guiding element attached to the pump side is made relatively large and requires complicated fabrication and machining necessitating that the pump be supported at a position relatively remote from the guide bar and there is possibility of leakage if the severe manufacturing tolerance thereof is not met.
Thus, there has long been a need for a submergible pump coupling system which is free from the drawbacks of the prior art.